Insulating a Floor

Insulating a floor will be most beneficial to homeowners where the floor is above a cold space. A cold space is any unheated or unused room as these can cause buildings to lose a lot of heat very quickly. Bedrooms above garages and houses with basements or cellars are the most common examples of this. These types of rooms often mean the room above it has suspended floors, which can be extremely easy to install floor insulation for. It’s widely accepted that floors that are solid, usually concrete, are harder to insulate and costlier to insulate. Floor insulation is something that can be done by most homeowners without the need to call in a professional. It is recommended however that you bring in a qualified electrician if when installing floor insulation, you need to move electric sockets to raise them higher.

1. Insulating a suspended floor

2. Insulating a solid floor

3. Other tips for insulating a floor

Floor Insulation for Suspended Floors

To identify if you have a suspended floor you need to assess whether there is a void beneath your floorboards and the floorboards themselves are resting over joists. This void can cause a lot of heat loss if it’s not addressed so filling this void with floor insulation such as insulation roll or insulation board can minimise household bills and make your home more comfortable too.

insulation-nettingSuspended floor insulation is the easiest to fit when there is a cellar or basement beneath the property. This should give easy access to the void below the joists, so insulation can be fixed in place using insulation netting. insulation slab or insulation board can be friction fit into the joists so that the insulation stays put whilst insulation netting is rolled out and fixed at each joist just for some extra support. By pulling the netting taught and ensuring the insulation is tightly packed into the space you can reduce heat loss through the floor without needing to lift a single floorboard.

Unfortunately, if your home doesn’t feature a basement or a cellar, but the floor is still suspended, floorboards and any floor finishings will need to come up. Since it’s a big job to empty a room of furnishings to gain access to the void below, we recommend that this is done alongside other big jobs like plastering or painting.

Like insulating a floor where a basement or cellar provides access to the joists, you need to lift the floorboards and put them to one side before laying rigid insulation boards in the joist spaces. Cut each piece of insulation board to just slightly smaller than the joist space you’re going to fit it into, this will provide friction for a tight fit, so no air can escape through the side gaps.

You can use insulation roll like popular natural insulation sheep's wool by fitting inexpensive insulation netting underneath the joists as in the picture to the right. Drape the netting as low as needed to accommodate the thickness of the insulation roll then roll the insulation out as usual, taking care to make sure it extends to the width of the joists.

Please be aware of airbricks in outside walls. Floorboards will rot if airbricks are covered as there will be no ventilation! These should be at least 2 inches below the bottom of the insulation before the hardcore.

insulation-board insulation-netting insulation-slab natural-insulation
 

Floor Insulation for Solid Floors

Solid floors in theory shouldn’t need as much insulation as suspended floors as they’re thicker and harder for heat to escape through. Stone floors can be as much as 50cm thick in old builds! However some heat can still be lost through these types of floors so it’s good to assess the options and weigh up the benefits of a warmer, more efficient floor.

Obviously with a solid floor you’re unable to remove the floor to insulate so the only method of insulating a floor is to layer up. It’s advisable to install a damp proof membrane between the solid floor and the insulation to ward off any unwanted moisture. Wet insulation is even more inefficient than no insulation at all!

With the use of specialist build ups with acoustic matting and underlays, you can reduce echoes and airborne noise in buildings that are built from solid walls and typically spacious inside like older churches that either need insulating or are being converted. For example, once insulation board has been laid across a solid floor, install a 1.2mm thick layer of acoustic barrier mat followed by a 9mm thick layer of acoustic MDF sheet to reduce the airborne noise and echoes whilst adding just 10.2mm to the floor thickness.

One thing that’s very important to consider is the floor level. With a minimum of three layers going on top of the existing solid floor, that can impact the height of the internal floor and affect other fixtures and fittings. It may be appropriate to trim doors to size and to employ an electrician to raise electric sockets.

Damp-Proof-Membrane Chipboard acoustic-barrier-mat acoustic-mdf-sheet
 

Insulating a concrete floor

When building or renovating a new space, insulation should always be considered. From preventing damp, to reducing heat loss and aiding with noise dampening, below grade insulation is always important. When it comes to insulating a concrete floor, there are a number of options available to you, and each brings their own advantages to keeping your home warm. Here at Insulation Superstore we have a wide range of insulation products available, and all at our famously competitive prices.

PIR boards

PIR boards are one of the most popular forms of insulation available. Polyisocyanurate (PIR) boards are generally made from a foam type material, and used in the form of a rigid board. PIR boards come in a range of forms, for example bonded to plywood for use on timber flat roofs, bonded to OSB board for decking and new flat roofs, or plasterboard for increased speed of insulation in walls. However the most popular form of PIR boards, and one that is particularly useful for insulating a concrete floor, is a PIR board that is between two aluminium foil facings – these provide extra levels of insulation for improved thermal retention. 

PIR boards are also incredibly easy to install – they can be cut and shaped easily and are relatively lightweight. Take a look at our range of PIR boards from Celotex, the UK market leader in high performance PIR insulation. 

Insulation slabs

Insulation slabs are a more flexible material with good insulation properties, and are used in a wide range of applications. Typically highly dense, but easy to cut and lightweight, insulation slabs reduce the amount of heat passing through by trapping it within the structure. Insulation slabs are often chosen for use with concrete floors because they can be easily installed within a timber framework, installed on top of the concrete floor.

Here at Insulation Superstore we have a range of different insulation slabs available, from brands such as Rockwool and Knauf. Each brand has used the latest technology and development to create a product that is high performing yet practical and easy to install. 

EPS

Expanded Polystyrene (EPS) is a form of insulation that is manufactured using beads of foam. The beads are exposed to heat, which causes them to expand and bond together. This creates a closed cell structure, which creates a consistent layer resulting in a constant level of insulation across the whole floor. 

EPS is a good choice for insulating a concrete floor because it has a long term R value, alongside a consistent level of thermal resistance, and it is produced in easy to manage sheets to allow easy installation. 

Insulation Superstore offers EPS from brands such as Styrene and Jablite, market leaders in the EPS insulation industry.

XPS

Extruded Polystyrene insulation is form of insulation that is manufactured using an extrusion process. This results in a closed cell structure which has a smooth surface on the top and bottom, and prevents water from penetrating through the insulation board. 

XPS is generally considered as better suited to insulating a concrete floor than EPS because it is more vapour resistant than EPS, and more dense which provides extra stability but it is also higher in price, so people are still opting for EPS when they are on a budget. 

Installation tips for insulating a concrete floor

When insulating a concrete floor, we’d always recommend installing a damp proof membrane, between the solid floor and the insulation. When insulation gets damp, its insulating properties are significantly reduced, which can cause issues, but this damp can also cause further damage to your home. 

When installing insulation on a concrete floor, the insulation can either go above or below the concrete. 

Insulation above a concrete floor

Installing insulation above the concrete floor is beneficial when working on a renovation project, because it can be placed onto the floor without requiring excavation and relaying of the floor. Additionally, insulation that is above a concrete floor will help the room to warm up more quickly, but it will also cool down more quickly. 

When installing insulation on top of the concrete floor, the most common method of installation is as follows. Lay the damp proof membrane onto the concrete, followed by the insulation. Then lay moisture resistant chipboard, or a concrete screed to the top, which can then be covered by the flooring to finish. 

Insulation below a concrete floor

Generally, if possible, insulating concrete below the concrete floor is the best form of installation. This is because the concrete helps to absorb the heat much better, whilst also preventing the room from overheating. 

When installing insulation below the concrete floor, the most common method of installation involves the following. Firstly, there is a form of infill over the surface, such as sand which will prevent anything from puncturing the next layer. Next, lay a damp proof membrane over the sand, which will create an airtight membrane. The next step is to lay insulation, following which concrete can be laid. Finally the flooring can be laid on top. 


What else can I do to insulate a floor?

Gaps between floorboards and around skirting boards can allow heat to escape and cause a draft. Avoid this for just a few pounds by going around the edges with a moisture-resistant sealant.

Here at Insulation Superstore we have experienced advisors that can offer sound and sensible advice in regards to your project. Trained by manufacturers with the technical knowledge required to assist you, contact our advisors with build specifications, a blueprint of what you're looking to achieve, or even just a broad idea of what your aim is. Contact our advisors by using our live chat in the bottom right hand corner or by phoning us on 01752 692 206.

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